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(1) Field of the Invention
The invention relates to deicing compositions for removing ice from a surface which include either succinic acid or succinic anhydride, or both, and a neutralizing base such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide wherein the deicing compositions when mixed with water produce succinate salts in a reaction that rapidly releases sufficient heat to melt the ice on the surface and the succinate salts act as a deicer and freezing point depressant. In particular embodiments, the deicing compositions further include a glycol which inhibits reformation of the ice on the deiced surface. The deicing compositions are suitable and effective for airport applications in which corrosion of aircraft alloys and concrete runways are of concern.
(2) Description of Related Art
Chemical deicing is routinely used during the winter season to maintain safer mobility on highways, residential and commercial surface structures that include, parking lots, walkways, driveways, and the like. Airports and airbases also use a combination of mechanical devices and anti-icing chemicals to insure safe operations during the winter months.
Common road salt is the most widely used deicing chemical on highways. It is effective, inexpensive, reliable, and easy to store and apply. An estimated 10 million tons at $35/ton is used each year (In Highway Deicing: Comparing Salt and Calcium Magnesium Acetate, Special Report 235, Transportation Research Board Committee on the Comparative Costs of Rock Salt and CMA for Highway Deicing, Washington, D.C., (1991)). The major problem with road salt is that it is associated with costly damages to highway infrastructure, motor vehicles, and the environment. Structural damages include concrete degradation and steel corrosion leading to high maintenance expenditure. Foliage burns, soil compaction, and water contamination are some of the adverse environmental manifestations of sodium chloride use.
Due to the problems associated with the use of chloride salts as road deicing chemicals, a less harmful road deicing chemical, namely calcium magnesium acetate (CMA), has been commercialized (Miller, Ways to Help Bridges and Deicers Coexist: CMA Cuts Corrosion on Zilwaukee Bridge, Better Roads, (February 1993); Strawn, CMA has Role to Play in Critical Applications, Kuennen, Ed., Roads and Bridges, (March 1993)). Calcium magnesium acetate inhibits concrete degradation and corrosion. It is a low environmental impact deicer. The downside of CMA use is its cost, which at $925.00/ton, is 20 times as much as common road salt. Furthermore, it is not a very effective deicer.
ICEBAN is a recent development by Natural Solutions Corporation (100 Volvo Parkway, Suite 200, Chesapeake, Va. 23320). ICEBAN is a natural liquid concentrate residue prepared from the organic by-products from cheese making, the production of alcohol, or the wet milling of corn (U.S. Pat. No. 5,709,812, 5,709,813, and 5,635,101 to Janke et al. ). It is non corrosive and has good anti-icing and deicing properties. However, the most notable downside of ICEBAN is that it is formulated as a liquid deicer. Equipment currently used for spreading of deicers are configured for solid deicers. Switching to a liquid deicer requires equipment reconfigurations leading to significant capital investment in addition to the capital required for storage tanks. The viscosity of the liquid at low temperatures may pose additional problems.
European Patent EP82890136.5 to Kaes claimed that a dicarboxylic acid mixture consisting of adipic acid (30-35 wt %), glutaric acid (40-50 wt %), and succinic acid (20-25 wt %) in the form of a potash salt is suitable for airport deicing. Although this formulation, in liquid form, possesses acceptable deicing characteristics, it is corrosive to metals and, therefore, it does not comply with the standard for aircraft metals. It is four times more corrosive than potassium succinate toward dichromate treated magnesium, which is the aircraft metal alloy that is most susceptible to corrosion. Further, this product has never been commercialized.
The deicing chemicals discussed above penetrate or melt ice as a result of their tendency to form aqueous solutions that have lower freezing points. In an attempt to enhance this process, U.S. Pat. No. 4,692,259 to Roman; U.S. Pat. No. 4,400,285 to Gancy; and U.S. Pat. No. 4,425,251 to Gancy have disclosed formulations that release heat upon contact with water. The results are dual-action chemical deicers that melt ice using the heat from the exothermic reaction between the agent and water and using the freezing point depressant effect of the resulting solution.
U.S. Pat. No. 4,692,259 to Roman in its preferred embodiment presents a deicing composition that utilizes the heat of reaction of magnesium with water and the freezing point depressant effect of the resulting chloride salts.
U.S. Pat. Nos. 4,400,285 and 4,425,251 to Gancy combines the exothermicity of the contact between calcium oxide and water and the freezing point depressant effect of acetate salts to formulate dual-action deicers.
Such inventions have endeavored to formulate deicers that posses a short term exothermic response and a long term freezing point depression effect which act in a complimentary fashion to infuse a superior ice-melting function to deicers. However, the invention disclosed by U.S. Pat. No. 4,692,259 to Roman contains chloride salts. Chloride induced corrosion of metal and degradation of concrete is well documented (Miller, Ways to Help Bridges and Deicers Coexist: CMA Cuts Corrosion on Zilwaukee Bridge, Better Roads, (February 1993); Strawn, CMA has Role to Play in Critical Applications, Kuennen, Ed., Roads and Bridges, (March 1993)). In the presence of adequate moisture and oxygen, chloride ions accelerate the corrosion process by increasing the conductivity of solutions. In addition, chloride salts, especially calcium and magnesium chloride, increase the metal-moisture contact time thereby promoting the corrosion process. In addition, there is clear evidence for the cumulative and long-lasting impact of chloride salt on the environment (Strawn, CMA has Role to Play in Critical Applications, Kuennen, Ed., Roads and Bridges, (March 1993)). Salt-mist and salt solutions damage roadside vegetation. Salt solution run off causes soil compaction and high salinity reducing soil fertility and permeability leading to loss of vegetation followed by soil erosion. Both California and New York have had to take extraordinary steps to curtail the impact of road salt to the Tahoe National Forest and the Adirondack Park, respectively. Therefore, any deicer, regardless of whether it is conventional or dual-action, will have no appeal to niche markets where it is absolutely essential to minimize degradation of structures due to corrosion and minimize loss of vegetation and habitats.
The dual-action formulations disclosed in U.S. Pat. No. 4,425,251 to Gancy and U.S. Pat. No. 5,334,323 to Schrimpf et al. contain acetate salts. Acetate salts have been shown to be safer alternatives to chloride salts. Acetate-based deicers such as CMA are non corrosive toward steel and aluminum and have little or no impact on the environment. However, acetate salts are too expensive for general use on road structures and are not suitable for application on airports, airbases and airplanes.
Presently, aircraft deicing is carried out by applying propylene glycol based deicing fluids. These fluids are sprayed on aircraft to lift accumulated ice and it is believed that propylene glycol prevents ice buildup. Numerous composition and method patents exist on this application and have been disclosed in U.S. Pat. No. 4,191,348 to Holwerda; U.S. Pat. No. 4,254,821 to Matsuda et al.; U.S. Pat. No. 4,573,802 to Kerrigan et al.; U.S. Pat. No. 4,826,107 to Thornton-Trump.; U.S. Pat. No. 5,096,145 to Phillips et al.; U.S. Pat. No. 5,244,168 to Williams; and U.S. Pat. No. 5,845,848 to Amako et al. Propylene glycol, in general, is not considered to be an effective deicer. It is regarded as an anti-icer that prevents ice buildup. Many inventors have claimed methods to preheat the anti icing fluids consisting of glycols to force deicing action. These methods employ a heat source and a heat exchanger, in numerous configurations, to supply heat prior to application. They are not suitable for rapid deployment notwithstanding the costs involving the use of an external heat source.
With regard to snow and ice removal at airports and airbases and on aircrafts, chemical deicing has not been practiced widely because of the lack of a chemical deicing agent that complies with the aircraft metal standards. Airport and airbase deicers need to comply with stringent criteria. These criteria are set to protect specialty alloys used in aircrafts in structurally critical areas. Therefore, a need remains for a chemical deicer that is effective at removing ice and which complies with the standards required for deicers intended to be used in deicing operations on and around aircraft.
The invention provides deicing compositions for removing ice from a surface which include either succinic acid or succinic anhydride, or both, and a neutralizing base such as sodium hydroxide or potassium hydroxide wherein the deicing compositions when mixed with water produce succinate salts in a reaction that rapidly releases sufficient heat to melt the ice on the surface and the succinate salts act as a deicer and freezing point depressant. In particular embodiments, the compositions further include a glycol which inhibits reformation of the ice on the deiced surface. The deicing compositions are suitable and effective for airport applications in which corrosion of aircraft alloys and concrete runways are of concern.
Therefore, the present invention provides a process for inhibiting or reducing icing or snow on a surface which comprises (a) mixing as reactants an acidic succinate compound and a base in an aqueous solution to produce a succinate salt at a pH between 4 and 11 as the deicing composition, wherein the reactants heat the solution; and (b) applying the heated solution to the surface to rapidly melt ice and snow.
The present invention further provides a process for producing a heated solution for applying heat to a surface to melt ice or snow which comprises (a) mixing as reactants a pre-measured acidic succinic compound and a base into an aqueous solution to produce a succinate salt at a pH between about 4 and 11; and (b) transferring the heated solution so as to apply heat to the surface for melting ice and snow.
In a further embodiment of the process, the compounds are in a dry, granular form and are in at least one container for use in step (a).
In particular embodiments of the above processes, the acidic succinic compound is selected from the group consisting of succinic anhydride, succinic acid, and mixtures thereof. Further still, it is preferable that the base is selected from the group consisting of an alkali metal, an alkaline earth metal, a hydroxy organic base, and mixtures thereof. In a further preferred embodiment, the base is selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, and mixtures thereof. In a further embodiment, a polyhydric alcohol anti-icing organic compound is mixed with the solution applied in step (b). Preferably, the polyhydric alcohol is a glycol selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol propylene glycol. More preferably, the glycol is propylene glycol.
Further still, the present invention provides a kit for use in producing a heated solution which comprises (a) at least one container of pre-measured amounts of compounds which react exothermally to produce a succinate salt at a pH between about 4 and 11 when combined with predetermined amounts of water to produce the heated solution, wherein the compounds are an acidic succinate compound and a base; and (b) instructions in the kit for combining the compounds with water to produce the heated solution.
Further still, the present invention provides a kit for sale as a unit in producing a heated solution which comprises pre-measured amounts of compounds which react exothermally to produce a succinate salt at a pH between about 4 and 11 when combined with predetermined amounts of water to produce the heated solution, wherein the compounds are an acidic succinic compound and a base. The kit is particularly useful as a warming device for use as a hot pack for medical treatments, hand warmers, seat warmers, and food warmers.
In a further embodiment of the kit, the kit contains an additional container of water to combine with the components.
In an embodiment further still, the compounds which react are contained in separate containers which are sold as a unit.
In a further still embodiment of the kit, the containers have an openable seal between the containers for mixing.
In a further embodiment of the kit, the compounds are in a dry, granular form.
In a preferred embodiment, the acidic succinic compound is selected from the group consisting of succinic anhydride, succinic acid, and mixtures thereof. In a further preferred embodiment, the base is selected from the group consisting of an alkali material, an alkaline earth metal, a hydroxy organic base, and mixtures thereof. In a further preferred embodiment, the base is selected from the group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide, and mixtures thereof. In a further embodiment of the kit, the kit further includes a polyhydric alcohol anti-icing organic compound. Preferably, the polyhydric alcohol is a glycol selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol propylene glycol. More preferably, the glycol is propylene glycol.
Therefore, it is an object of the present invention to provide heated deicing compositions that are effective at melting ice on a surface and which comply with the standards required for deicers intended to be used in deicing operations on and around aircrafts.
It is a further object of the present invention to provide heated deicing compositions that are effective at melting ice on a surface and which are minimally corrosive to metal alloys and concrete.
It is a further object of the present invention to provide heated deicing compositions that are effective at melting ice on a surface and which inhibit the reformation of ice on the surface.
These and other objects of the present invention will become increasingly apparent with reference to the following drawings and preferred embodiments.